It is required for an image display surface of displays of, for example, TVs, PCs, mobile phones, GPS (global positioning system), car navigations, graphics tablets, CAD (Computer aided design system), handheld game machines, portable audios, etc. to decrease reflection from light ray irradiated by external light source such as fluorescent light, sunlight, etc., and increase its visibility. Conventionally, by providing an antireflection film on the display surface of a display utilizing the phenomenon that the reflectiveness decreases when a surface of a clear object is covered by a clear film (low refractive index layer) having low refractive index, the reflectiveness of display surface is decreased and the visibility is improved.
As one way of lowering refractive index, there is a method of containing air having a refractive index of 1 inside of a low refractive index layer. For example, in Patent Literature 1, hollow particles, the inside of which are porous or hollow, are used to decrease the refractive index of a refractive index layer.
In such a low refractive index layer containing hollow particles, the hollow particles are effective for lowering refractive index, however, there are problems that the hardness of the hollow particles is low since the inside of the hollow particles are porous or hollow, thus, the hardness and abrasion resistance of the low refractive index layer itself is low. Particularly, if the hardness or abrasion resistance is low, the surface of the low refractive index layer is easily damaged when a sharp object contacts the surface, and when the surface is damaged, the visibility of the antireflection film decreases and it leads to the deterioration of the appearance.
With respect to this problem, Patent Literature 1 suggests using solid particles, the inside of which is neither porous nor hollow, having superior hardness to hollow particles, and further modifying the surface of the hollow particles and the solid particles with crosslink-forming groups having similar structure. Thereby, Patent Literature 1 mentions that the cross-linked hollow particles and solid particles are uniformly and densely filled in a low refractive index layer, and by the crosslinking, the abrasion resistance of the low refractive index layer (anti-reflection laminate) can be improved.
However, such an anti-reflection laminate of Patent Literature 1 can have a good anti-reflective property, but has problems such as increase in cost and decrease in adhesion due to increase in the amount of solid particles to be used, since hollow particles and solid particles are uniformly and densely filled in the low refractive index layer.
In addition, an optical film (anti-reflection laminate) excellent in hardness and abrasion resistance besides having high anti-reflective property is required.